Blue Notes Blues (episode) is the 33rd overall episode of Tegami Bachi
Lag reads a book on the people of Blue Notes Blues who lived peacefully with the Maka. However, this ended when people's hearts were polluted by sin. Lag discovers a cave near the lake but is told not to enter by the townspeople. They take Lag and the others back to town.
When Lag asks about Noir, they confirm that Noir went to the cave, which is a path leading to Blue Notes Scale and the holy site. The mayor warns Lag not to enter as he will be punished severely. He explains the history of how the townspeople suffered when the geothermal energy around the town was stolen, leading to dead crops and widespread illness. A pregnant woman named Celica became greedy and decided to drink the water of the underground lake to gain immortality.
Accompanied by Celica's return, the town returned to normal. However, Celica became quiet and eventually gave birth to twins before she died, which are the children of Maka. Lag and Niche head to Blue Notes Scale where they find frozen gaichuu and discover that Noir was there luring one outside to kill. They venture further and find the lake where another child of Maka, Niche's Sister, appears.
This woman questions Niche on her forgotten memory. The mayor and townspeople follow after Lag, where they plead the Maka for forgiveness. Niche's sister tells them that the Maka lost the ability to converse with humans and they have no interest to do so. Then, she corrects Lag on the townspeople's story... Celica was actually forced to enter the cave to become a sacrifice for the Maka when the lack of warmth persisted, which was caused by the mining of spirit amber in the region. Celica begged the Maka to at least let her unborn child live.
For the first time, the Maka shed a tear for a human, and the tear blesses Celica. After Celica gave birth to the twins and died, the town declared them to be cursed and kept them isolated with only water as sustenance. Eventually, the town feared the existence of the twins would bring shame to them all; therefore, the mayor's ancestor threw the children into the frozen lake.